Cam fixture



Sept. 18, 1945. c. c. RUTBELL' CAM FIXTURE Filed Feb. 8, 1944 2 Sheets-Sheet 1 H #59 w 0 2 11 ll 2 4, g 3 7 I ll \U/ w 7 2 m M w @lililli U 0 T f m n m 2. F 0 w a w 6 M 3 w Q, a

ATTORNEY Sept. 18, 1945. c, RUTBELL I 2,385,030

CAM FIXTURE Filed Feb. 8, 1944 2 Sheets-Sheet 2 ATTORNEY Patented Sept. 18, 1945 4 'VUNITEDSTATESI PATENT OFFICE ClarenceC. Rutbell, Endicott, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application February 8, 1944, Serial'No. 521,531 3 Claims. (01. 90-243) This invention relates to an improved form of cam cutting device and more specifically to a cam fixture for supporting a blank to be cut as a tapered spiral cam in a shaper.

An object of the invention is to provide a cam fixture in which a master cam controls the cutting of a special cam shape.

Another object of the invention is the provision of a jig or fixture holder in which a cutter can be substituted for a follower roller in order to cut a master cam.

A further object of the invention is the provision of a swinging work holding frame which is pivoted with the fulcrum center at or near the surface to be cut.

A feature is the method of cutting a master cam in the jig in which it is to be used, comprising the steps of substituting a cutter for a follower roller and driving a normally idle follower roller shaft.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings: I

Fig. 1 is a side elevation view of thefixture.

Fig. 2 is a perspective view of a tapered cam which is an example of the kind of parts to be made with the use of the fixture f the invention.

Fig. 3 is a plan view of the fixture shown at an angle parallel with the axis of the cam shaft of the device.

The purpose of the device of the invention is to make possible the cutting of complicated cam shapes in a more rapid and accurate fashion. The part [0, Fig. 2, is seen to have a spiral cross section throughout its length and is further complicated by a tapering shape which slopes from the enlarged cam end ll down to an almost circular end l2. A circular hole I 3 extends through the part. Drilled into the large end I l is a locating opening [4 for orienting the cam on the fixture as well as on the apparatus in which it is used. It is required that the cam be very accurate with regard to the cam shape at any point along its length.

The fixture or jig is supported by a main frame or holder 20, Fig. 1, formed with a base flange 2| which has the usual slotted formations for securing the device to the work table of a shaper. Extending through a boss near the top of the frame 20 is a fulcrum bolt or pivoting shaft 22 which is the support for a swinging work holder member ratchet wheel '46.

23. Projecting from one side of member 23 is a pair of cars 24 and 25 which are shaped with aligned holes to serve as bearings for a work holding shaft 26.

Shaft 26 is formed with a shoulder 21 to which is pinned a lock washer 28. Another shoulder 29 is a base for reduced threaded portion 30 formed as the upper end of the shaft.

It is on portion 39 that the work piece or blank H! is fastened to be out. A locating pin 3| extends from shoulder 29 and fits into opening M, Fig. 2, to key the blank on the shaft 26 in an exact relation with reference to the large master or control cam 32 affixed to the other end of the shaft and keyed thereon by a Woodrufi key. A spanner nut 35 cooperates with washer 36 to hold the control cam on the lower end of shaft 26. At the upper end, a special hexagonal nut 31 serves to hold the blank ID on the shaft.

At about the middle of shaft 26 is fastened a rotating means in the form of a worm wheel 40. The teeth of this wheel, Fig. 3, are in mesh with a worm'4l mounted on a short shaft or stud 42 held on a bearing boss 43 extending from the swinging frame 23. A shoulder 44 on the stud is drawn tight against the face of the boss by a sunken nut threaded on a stud portion Within the frame and not shown. Formed as part of the worm barrel is a hub 45 to which is fastened a A nut 41 and washer serve to holdthe rotatable ratchet and worm assembly on the stud. In Fig. 1 is shown a knob 50 which is on wheel 46 for the purpose of rotating the worm manually when so desired, however, provisions are made to rotate the work automatically.

At the top of Fig. 1 there is shown in outline, part of the reciprocating head 5! of a shaper on which the fixture is used. When the head reciprocates relative to the fixed work blank II), it moves a cutting tool 52 over and into the surface of the blank to form it as required. It will be noted that the area or line of the blank worked upon is near the center of the pivot shaft 22 upon which the frame 23 is rocked. In this relationship, a fine adjustment of the contour of the work is possible with a relatively coarse variation of the outline of the master cam 32.

Fastened to any cyclically movable part of the shaper is an adjustable linkage which ends in a I link 55 formed with a ratchet tooth 56. Secured to the sides of link 55 are a pair of thin plates 51 for confining the reciprocating path of the end of the link to cooperate constantly with the ratchet wheel 46. A slide block 58 is fastened between the plates and near the end to prevent the link from riding off the ratchet wheel. During the working vibration of the shaper head, the ratchet link is pushed to the left, Fig. 1, to ratchet idly over the teeth on the wheel. Then, on the recovery stroke of the shaper head, link 55 is drawn towards the right and wheel 46 is turned clockwise with worm 4! to operate wheel 50 and turn shaft 26 and the work piece H) in a counterclockwise direction, Fig. 3.

As the master cam 32 is turned, it rests on a guide roller 60 and is lifted or lowered with reference thereto, depending on the shape of the cam. Of course, as the cam 32 is turned and lifted, the frame 23 carrying it is also lifted or swung clockwise, Fig. 1, about center 22 to vary the position of the cam blank I with respect to shape of the work is determined by the contour of the master cam. The rate of rotation of the work is controlled by determining the length of stroke of link 55 and the number of ratchet tooth spaces advanced for each stroke. The entire fixture is raised with respect to tool 52 by the usual vertical work table controls of the shaper.

Guide roller 60, Fig. 1, is rotatably mounted on a double ended bolt 6| extending through a cylindrical extension 62 on the main frame 20. A shoulder 63 is formed on the bolt and is drawn against the side of the frame by the nut 64 on the inner end of the bolt. Another nut 65 on the outer end of the bolt, confines a washer and a ball race 66 which is part of a ball bearing for roller 60.

As the swinging frame 23 rides up and down, it rubs against the side of the main frame and tends to wear the casting. To prevent this, a hardened wear plate is fastened to the main web of the frame and it is against this that a set of buttons 80 on frame .23 are allowed to ride.

The method of cutting and forming the maser cam 32 comprises the use of the fixture in which it is to serve as a control. In other words, cam 32 is first attached in the fixture in the shape of a blank, and is cut therein before being used as a master. When the master cam is to be out, roller 60 is removed and there is substituted a single pointed rotary cutter of the same outside diameter. This cutter is driven by gearing or belt and a cut is taken for each 10 graduation around the cam. The cam is spotted for cutting by the use of J ohansson gage blocks which are assembled because the cam is cut in the very same angular position in which it is to serve as a master.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a cam cutting fixture, a main frame, a swinging frame pivoted on said main frame, a shaft carried by said swinging frame, a guide member on said main frame, a master cam on said shaft and cooperating with said member, means for fastening a work piece to said shaft, a worm wheel on said shaft for rotating said master cam to change the position of the work piece, a worm for operating said worm wheel, and manipulative means for rotating said worm.

2. A device as set forth in claim 1 wherein the surface to be cut on the work piece is located coincident with the pivot center of the swinging frame.

3. In a cam cutting fixture for use in a shaper, a main fixture frame, a swinging frame pivoted on said main frame, a shaft carried by said swinging frame, a guide roller on said main frame, a master cam on said shaft and cooperating with said roller, means for fastening a cam blank to an exposed end of said shaft for cutting by said shaper, a worm wheel on said shaft, a worm for driving said wheel, a ratchet wheel attached to said worm, a pawl for operating said wheel, and an operating linkage for said pawl to operate it in synchronism with the operation of said shaper.

CLARENCE C. RUTBELL. 

